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单桩水平承载力是抵抗建筑物水平变形、桩基抗震计算的重要参数。水平静载荷试验一般为桩顶自由状态,而实际工程中筏形或者条形基础对桩顶有较强的约束作用;此外,现有设计方法基于弹性反力假设,桩身结构基于线弹性假定,未考虑桩身混凝土开裂对承载力的影响。采用混凝土塑性损伤模型,选取上海典型场地软土试桩验证后,进一步分析竖向荷载、配筋率、桩顶固接条件以及对灌注桩水平承载力影响。分析表明:竖向荷载对桩身混凝土的压应力有利于提高单桩水平承载力;提高配筋率能在一定程度上提高单桩水平承载力,改善后期变形以及桩身延性;桩顶固接约束能够有效提高单桩水平承载力。弹性地基反力m法计算得到桩顶固接与自由状态水平承载力比值与本文差异较大,桩顶固接对水平承载力提高程度有待试验进一步验证。
The horizontal bearing capacity of single pile is an important parameter to resist the horizontal deformation of the building and the seismic calculation of pile foundation. The horizontal static load test is generally free-standing at the top of the pile, while the raft or strip foundation is strongly restrained on the pile top in actual engineering. In addition, the existing design method is based on the assumption of elastic reaction and the pile structure is based on the linear elasticity assumption , Without considering the impact of pile concrete cracking on the bearing capacity. The plastic damage model of concrete is adopted to select the typical test site for soft soil in Shanghai to verify the vertical load, reinforcement ratio, fixing conditions of pile top and the horizontal bearing capacity of bored pile. The analysis shows that the compressive stress of vertical load on pile concrete is beneficial to improve the horizontal bearing capacity of single pile; increasing the ratio of reinforcement can improve the horizontal bearing capacity of single pile and improve the post-deformation as well as the ductility of pile; Constraints can effectively improve the single pile horizontal bearing capacity. The ratio of the horizontal bearing capacity between the top of the pile and the free state calculated by the elastic foundation reaction force m method is quite different from that of this article. The degree to which the top of the pile is fixed to the horizontal bearing capacity needs to be tested further.